For each line on your BOM (Bill Of Materials) you can approve multiple different parts. The CircuitHub quote tool will then select the optimal part based on pricing and availability at the currently selected Assembled Board qty and Lead Time.

The part currently selected by the quote tool is shown is shown by the tick symbol.

As you move the quote sliders around you will see the optimal part being selected by the quote tool.

It is important that you only add parts to the Approved Parts List that are valid for the particular BOM line you are working on.